In recent years, a brain dock (brain medical checkup) using MRI (Magnetic Resonance Imaging) or CT (Computed Tomography) has been widely performed. In the brain dock, cross-section images of a brain are obtained by MRI or CT, and the state of the brain is determined based on the cross-section images of the brain. By performing the brain dock, it is possible to know the state of the blood vessels in the brain and thereby find signs of brain diseases such as brain infarction, brain hemorrhage and the like.
Further, with the cross-section images of the brain obtained by MRI or the like, it is possible to know not only the state of the blood vessels in the brain but also the state of each part of the brain, so that it is possible to also find signs of a specific disease unrelated to the blood vessels. For example, it is known that a patient with shrunken frontal lobe or the like has an increased chance of developing dementia.
Japanese Unexamined Patent Application Publication No. 2005-230456 discloses a method in which a gray matter image is created based on MRI images obtained by photographing the brain of a subject, and the created gray matter image is compared with a gray matter image of a normal person to determine the shrinkage of a specific part to thereby find signs of dementia or the like.